This document discusses intellectual disabilities (ID), including definitions, causes, diagnosis, and treatment. ID is characterized by limitations in both intellectual and adaptive functioning that originate before age 18. Causes can include genetic conditions, illnesses, injuries, or environmental factors. Diagnosis involves assessing intellectual and adaptive functioning. Treatment focuses on early intervention, special education, accommodations, and addressing any co-occurring conditions. Common types of ID discussed include Down syndrome, fragile X syndrome, fetal alcohol spectrum disorder, autism, and shaken baby syndrome. Rarer conditions like Prader-Willi syndrome and Angelman syndrome are also mentioned.

1. Alejandra Fernandez, Alejandra Gonzalez, &
Jessica Craig
INTELLECTUAL DISABILITIES

2. An intellectual disability (ID), formerly called mental retardation
(MR) is inadequate intellectual functioning (Santrock,2016).
Children with an ID learn and develop more slowly than other
children. ID affects two functioning areas, intellectual functioning
and adaptive functioning. Intellectual functioning deals with
things such as learning, problem solving, and judgment. While
adaptive functioning affect activities with daily life such as
communication and independent living. About one percent of the
population are affected with an ID and of that one percent 85
percent have a mild ID. It is unclear why, but males are more
likely than females to be diagnosed with an ID (APA, 2017).
WHAT IS AN INTELLECTUAL
DISABILITY

3. ID is a condition of limited mental ability. About 5 million Americans fit this
definition of intellectual disability. For individuals to meet qualification for an
ID diagnose they must,
(1) have a low IQ, below 70 on a traditional intelligence test
(2) have difficulty adapting to the demands of everyday life
(3) exhibit these characteristics by age 18 (Hodapp & others, 2011).
The age limit is included in the definition of ID because accidents after this
time period that affect the individuals intelligence is not given a diagnose of
ID.
INTELLECTUAL DISABILITY
QUALIFICATION

4. CLASSIFICATION OF INTELLECTUAL
DISABILITY BASED ON IQ
Type of
Intellectual Disability
IQ
Range
Individuals with an
Intellectual Disability
Mild
Moderate
Severe
Profound
55-70
40-54
25-39
Below 25
89%
6%
4%
1%

5. Intermittent
Limited
Extensive
Pervasive
• Episodic or short-term support is as
needed during life-span.
• Supports may be intense and quite
consistent over time. Support is limited
but not intermittent. Most likely for
adaptation from school-to-adult period.
• Support is regular on a daily basis and are
not time limited.
• Support level is intense and constant
across settings. Some support may be of
life-sustaining nature.
Classification of
Intellectual Disability
Level of Support Needed
CLASSIFICATION OF INTELLECTUAL
DISABILITY BASED ON LEVELS
OF SUPPORT NEEDED

6. MOST COMMON TYPES OF
INTELLECTUAL DISABILITIES
• Fragile X syndrome (FXS)
• Down syndrome
• Fetal alcohol spectrum disorder
(FASD)
• Autism Spectrum Disorder (ASD)
• Shaken baby syndrome (SBS) or
Abusive Head Trauma (AHT)

7. Fragile X syndrome (FXS) is the leading
inherited cause of intellectual disability. It
is associated with a range of social,
behavioral, and cognitive impairments.
FXS is the most common inherited cause
of ID worldwide. FXS is caused by a
mutation of the fragile-X mental
retardation (FMR-1) gene located on the X
chromosome
Males are usually more severely affected by
FXS than females. Affected individuals
usually have delayed development of
speech and language by age 2.
FRAGILE X SYNDROME (FXS)

8. Down syndrome is a genetic condition
that causes delays in physical and
intellectual development. It is the most
common identifiable cause of
intellectual disability. Around 15-20%
of the intellectual disability population
have down syndrome. The majority of
children with down syndrome have
mild to moderate intellectual disability.
Some show no sign of having an
Intellectual disability others may have
severe intellectual disability. People
with Down’s syndrome are believed to
have always existed.
DOWN SYNDROME

9. Fetal Alcohol Syndrome (FAS) is one
of the leading causes of preventable
birth defects and intellectual
disabilities
FASD can cause physical and mental
disabilities and the levels of severity
varies. Depending on how bad the
child's alcohol effects are their
disability can be mild to severe.
FETAL ALCOHOL SPECTRUM
DISORDER (FASD)

10. Autism Spectrum Disorder (ASD) is
a pervasive developmental disorder
that affects numerous areas of
functioning. The primary symptoms
are deficits in social communication
and social interaction, and restricted,
repetitive patterns of behavior,
interests or activities. About 10% of
individuals with Intellectual
Disability have ASD or autistic traits.
AUTISM SPECTRUM DISORDER (ASD)

11. Shaken baby syndrome (SBS) or
Abusive Head Trauma (AHT) is
caused by vigorous shaking of an
infant or young child by the arms,
legs, chest or shoulders. The
vigorous shaking can result in brain
damage that lead to intellectual
disability, speech and learning
disabilities, paralysis, seizures,
hearing loss and even death.
SHAKEN BABY SYNDROME (SBS) OR
ABUSIVE HEAD TRAUMA (AHT)

12. • Prader-Willi Syndrome (PWS)
• Wolf-Hirschhorn syndrome
• Angelman syndrome (AS)
RAREST TYPES OF
INTELLECTUAL DISABILITIES

13. Individuals with Prader-Willi
syndrome have mild to moderate
intellectual disability. About 40% of
individuals with Prader-Willi
syndrome have a mild intellectual
disability and around 20% have a
moderate intellectual disability. IQ
for this syndrome are estimated to
range between 50 and 85 with a
mean of 60.
PRADER-WILLI SYNDROME (PWS)

14. Wolf-Hirschhorn syndrome results
from an error on a part of the gene
known as chromosome 4p. This
syndrome is not an inherited genetic
disorder in most cases but rather a
spontaneous mutation that occurs.
This syndrome is a rare condition
that is estimated to occur in one in
every 50,000 births.
WOLF-HIRSCHHORN SYNDROME

15. Angelman syndrome is a
multifaceted genetic disorder that
mostly affects the nervous system.
Some common characteristic of this
condition include delayed
development, intellectual disability,
severe speech impairment, and
problems with movement and
balance.
ANGELMAN SYNDROME (AS)

16. Sometimes an intellectual disability is caused by an environmental factor or
other causes. These causes can be quite varied but can include:
• Problems during pregnancy such as viral or bacterial infections.
• Complications during birth
• Exposure to toxins such as lead or mercury
• Complications from illnesses such as meningitis, measles or whooping
cough
• Malnutrition
• Exposure to alcohol and other drugs
• Trauma
• Unknown causes as well
ENVIRONMENTAL & OTHER
CAUSES

17. Intellectual disability is identified by problems in both intellectual and adaptive functioning. Doctors can
assess for intellectual functioning through exams and standardized testing. An IQ test score is no longer
required for diagnosis. Standardized testing is also used for diagnosing the condition. IQ score may not
accurately reflect overall intellectual functioning.
Areas of adaptive functioning:
Conceptual – language, reading, writing, math, reasoning, knowledge, memory
Social – empathy, social judgment, communication skills, the ability follow rules and the ability to make
and keep friendships
Practical – independence in areas such as personal care, job responsibilities, managing money, recreation
and organizing school and work tasks
Family members, teachers, and caregivers take part in the adaptive functioning assessment. Intellectual
disability is identified as mild, moderate, or severe. Symptoms of intellectual disability usually begin during
childhood or adolescence. Some delays in language or motor skills are noticeable by age two. Mild levels of
intellectual disability may not be identified until the child starts school and has difficulty with academics.
DIAGNOSIS

18. There are many different causes of intellectual disability. Intellectual
disabilities can be associated with a genetic syndrome, for example, Down
syndrome and Fragile X syndrome. Sometimes intellectual disabilities may
develop following an illness such as meningitis, whooping cough or measles. It
can also result from head trauma during childhood, or from exposure to
toxins such as lead or mercury. Other factors like brain malformation,
maternal disease and environmental influences like alcohol, drugs or other
toxins can also contribute to intellectual disabilities . Labor and delivery
related events such as infection during pregnancy and problems at birth, or
not getting enough oxygen, can also causes of intellectual disabilities.
CAUSES

19. Intellectual disability is a life-long condition. With early and continuing intervention the individual
can improve functioning and enable them to succeed throughout their lifetime. Once a diagnosis is
made, assistance is offered and is focused on the individual’s strengths and needs. The individual
receives the support he or she needs to function at home, in school/work and in the community.
The Individuals with Disabilities Education Act, (IDEA) (1990), enforces by law that early
intervention services to identify and help infants and toddlers with disabilities be offered. Federal
law ensures that special education and related services are available free to every eligible child with a
disability.
Co-occurring conditions
Some mental health, neurodevelopmental, medical and physical conditions frequently co-occur in
individuals with intellectual disability, including cerebral palsy, epilepsy, ADHD, autism spectrum
disorder and depression and anxiety disorders. Identifying and diagnosing co-occurring conditions
can be challenging, for example recognizing depression in an individual with limited verbal ability.
However, accurate diagnosis and treatment are important for a healthy and fulfilling life for any
individual (Friendship Circle, 2012).
Click on the tab children with special needs guide at the top of the homepage for more
information on resources and other topics.
TREATMENT

20. Santrock, J. (2016). A topical approach to lifespan development. (8th ed.). New York, NY:
McGraw-Hill Education.
https://www.nidcd.nih.gov/health/speech-and-language
https://www.psychiatry.org/patients-families/intellectual-disability/what-is-intellectual-
disability
https://www.hwns.com.au/about-us/about-disability/types-of-disabilities/types-of-
intellectual-disabilities/
https://www.thearc.org/learn-about/intellectual-disability
https://www.friendshipcircle.org/blog/2012/05/22/13-chromosomal-disorders-youve-
never-heard-of/
https://rarediseases.org/rare-diseases/megalocornea-intellectual-disability-syndrome/
REFERENCE